Grinding and polishing and the like



Now 13, 1956 H. WHITESELL- 2,770,082

GRINDING AND POLISHING AND THE LIKE Filed Aug. 31, 1953 8 Sheets-Sheet iNov. 13, 1956 Filed Aug. 31, 1953 8 Sheets-Sheet 5 Nov. 13, 1956 H.WHITESELL 2,770,082

GRINDING AND POLISHING AND THE LIKE Filed Aug. 31,' 1953 8 Sheets-Sheet4 Nok 13, 1956 H. WHITESELL GRINDING AND POLISHING AND THE LIKE 8Sheets-Sheet Filed Aug. 51, 1953 .3 FTalL FT Z3.

invem-or': Hry M1256,

Nov. 13, 1956 H. WHITESELL GRINDING AND POLISHING AND THE LIKE 8Sheets-Sheet 6 Filed Aug. 31, 1953 Nov. 13, 1956 H. WHITESELL GRINDINGAND POLISHING AND THE LIKE 8 Sheets-Sheet 7 Filed Aug. 31, 1953 H932Invenfgr:

Nov. 13, 1956 H. WHITESELL GRINDING AND POLISHING AND THE LIKE 8Sheets-Sheet 8 Filed Aug. 31, 1953 United States Patent GRINDING ANDPOLISHING AND THE LIKE Harry Whitesell, Chicago, Ill.

Application August 31, 1953, Serial No. 377,521

17 Claims. (Cl. 51-141) This invention relates to improvements ingrinding and polishing, and the like. The invention relates to both theimprovements in grinding and polishing operations and the process ormethod of conducting the same, and also to the means which I havedevised for conducting such improved operations. The followingintroductory statement will facilitate an understanding of the presentimprovements and assist in differentiating said improved operations frompreviously known and practised grinding and polishing operations:

Grinding and polishing operations are closely related to each othereachinvolves the removal of material from the stock or work article by anabrasive action, and the difference between the two operations asgenerally known resides rather in degree than in kind. That is to say,in each case the removal of material is effected by abrasion, but in thecase of grinding operations such removal is generally at a higher ratethan the rate used in the polishtion. This difference in degree or rateof material removal imposes substantial differences in the operational.

conditions under which the abrasion is effected. These operationaldifferences may include both the abrasive material used, and thepressure which is applied between such abrasive material and the work orobject being treated.

Usually a lighter contact pressure is used between the work and theabrasive surface when conducting a polishing operation than is used whenthe operation is one of grinding. However, it is generally desirable toso conduct the polishing operation that the scratches created on thework surface are longer and lighter than the scratches created duringthe grinding operation. That is to say, in polishing the scratch strokesare usually produced under a lighter pressure than is used whengrinding, and conversely, the scratches produced in the polishingoperation represent longer work strokes. Such longer work strokes andscratches of the polishing operation serve to eliminate theirregularities of surface produced during the grinding operation, inwhich grinding operation the material is generally removed more rapidlyand with a deeper abrasive cut, being somewhat in the nature of agouging out of the surface of the work being treated. The lighter thepressure used in the polishing operation,

and the longer the polishing scratches (which are very minute inthemselves) the finer the polishing and finishing operation which may beproduced.

Generally in the past it has been customary to conduct grinding andpolishing operations on a given object or piece of work by use ofabrasive surfaces of different degrees of coarseness. Thus it has beencustomary to use a coarser abrasive surface when grinding than whenpolishing, and vice versa. However, since the difference betweenpolishing and grinding is largely a matter of tie gree, and since thepolishing operation is performed by use of a lighter contact pressureand longer scratches than are used in the performance of a grindingoperation on that same object, it is possible to effect both grindingand "ice polishing operations on a given object by use of the sameabrasive surface, provided that said surface be not too coarse. It isalso possible to conduct both the grinding and polishing operationssimultaneouslythat is, as a single properly co-ordinated operation-byuse of the equipment or means hereinafter described, and when conductedaccording to my improved method or operation.

My improved operations and the means to practise the same, are primarilyintended for use in connection with belt type operations andmachinesthat is, operations wherein the work is held against a rapidlytravelling belt or tape, which belt is provided with an abrasive surfaceagainst which the work is held and pressed. Usually such operationsinclude two pulleys or wheels over which the belt loop travels, the beltbeing retained under desired tension by suitable means to draw one orboth of the pulleys away from the other. Usually, also, spring means isprovided in connection with such tension arrangements so that slightback and forth movements of one or both of the pulleys may occur duringthe conduct of the operations.

When using such an arrangement as that just referred to it is customaryto hold and press the work against such belt abrasive surface at thelocation of one of the pulleys or wheels, which is referred to as thecontact wheel. By providing the belt surface of such wheel with aslightly yieldable surface, such as a layer or rubber or the like,smooth running of the abrasive surface during contact of the worktherewith is ensured, and slight yield of such .wheel surface ispossible during the conduct of the operation. However, it isnevertheless true that all portions of the wheels peripheral surface,with such an arrangement, are of the same softness or yieldability, bothperipherally or around the wheel, and axially or across the wheelsurface.

Usually the abrasive belt used in such operations is rather thin andsufficiently pliable to permit such belt to closely accommodate itselfto slight variations in the wheels peripheral contour during running,and during the abrading contact of the work against such belt surface atthe location where the work presses against the belt which is running onthe wheel. Due to this circumstance a working pressure of the work bodyagainst the abrasive belt (while said belt is travelling over the wheel,such abrasive pressure being exerted against the belt at a loca tionwhere the belt is travelling on the wheel surface) acts to slightlydepress the belt. by compression of the yieldable surface of the wheel.If the work surface which is pressed against the abrasive belt is fiat,then there will be produced a slight depression and deformity of thebelt at the location of such pressure, and such deformity andv its areaof contact with the abrasive belt will be determinedby the length of thechord which intersects the to a maximum, and then decrease to zero atthe trailing end ofthe chord. Such deformity will be transmitted throughthe thin belt to the elastic peripheral surface of the wheel on whichthe belt rides.

It is now to be noted that under the foregoing operating conditions,however, in which the wheel surface is of a uniform degree of softness,a given length of chord of contact of the work against the abrasive beltwill always represent the same amount of pressure of such work body.

against the abrasive belt surface. Thus the ratio between V length ofchord and amount of pressure of the work body against the abrasivesurface must remain constant in the case of such previously known andused arrangements.

The length of chord referred to in the foregoing statement is also ameasure of the length of scratch produced on the work body'surface.Therefore in orderto increase the length of that scratch (as for theproduction of a polishing operation), under the pressure of the workagainst the abrasive surface, under the conditions assumed, it isnecessary to increase the pressure of the work against such abrasivesurface. This is undesirable, beyond a certain pressure condition, if agood polishing operation is to be secured. Therefore, when the yieldablewheel surface is homogeneous in character, and of substantially uniformsoftness over the entire peripheral or belt sustaining surface of thewheel, it is evident that a limitation. is imposed on the abrasiveoperations which may be conducted with such arrangement, sincethepressure of the, work against the abrasive surface must not exceed anamount which is, consistent with production of the desired finish on thework surface. Also, that finish which can be produced will be determinedlargely by the coarseness of the abrasive surface of the belt used inthe operation. Thus, such an arrangement, which is customary in the artat the present time, must be practically limited in its use, to oneparticular operation, such as grinding or polishing, and even tosub-divisions of these two, and it becomes necessary to conduct thegrinding and polishing operations on belts of different degrees ofcoarseness, or contact wheels whose homogeneous surfaces are of,different degrees of softness as required for the specific operations tobe conducted. on them.

Thus it is true that under present and conventional operations asconducted by the use of such equipment (wherein the surface of thecontact wheel is substantially homogeneous and of substantially uniformsoftness over its entire area), it is necessary to conduct the differentoperations of grinding and polishing (and sometimes, in termediateoperations) by use of different abrasive belts and/or different contactwheels, making it necessary to either change the wheel and belt of aninstallation when another operation is to be conducted, or to providedifferent complete grinding equipments for the different operations. Inany case. it is evident that severe limitations are imposed on. the useof such equipment, when the contact- Wheels are provided withhomogeneous contact surfaces of substantially uniform softness overtheir entire working areas.

According to my present improvements I provide the contact wheel with abelt carrying working surface which is. composed of numerous areas orsections of different degrees. of softness so that under the pressureexerted by abrasive contact of'the work withthe abrasive belt riding onsuch wheel said belt will be deformed by varying amounts as thesevarious areas of different degrees of softness "come into registry withthe area of engagement of the belt with the Work elementbeing'abrasively treated;

Under this operation, as a relatively soft area of the wheel surfacecomes into operation the deformation will be larger than that producedwhen a relatively less soft wheel area is in operative relation to thebelt. and the Work. These areas of differentor'varyingdegrees ofsoftness are interspersed over'the' peripheral belt contacting surfaceof the wheel in such manner that as the wheel rotates with belt travel,the work location being substantially unchanged, the different softnessareas are successively bnought into play, thus producing a combinedeffect on the operation. Thus the abrasive effect is one produced by arapidly changing softness effect, and a corresponding rapidly changingamount of deformation of the belt at the location of contact of the beltwith the work.

It has been pointed out that the lengths of the abrasive scratchesproduced on the work, for a given pressure of that work against thebelt, depend on the lengths of the chords of abrasive "contact at thelocation of the operation; and when the successive wheel surface areasare'thus' of varying degrees of softness it is evident that varyinglengths of scratches will be produced on the work section being treated,some long when the wheel surface is relatively soft, others shorter whenthe wheel surface is relatively hard. Thus a combined grinding andpolishing action is produced on the work section being treated, and infact varying degrees of grinding and polishing action will be producedin rapid succession on the work section, as a more or less continuousand uninterrupted operation.

The different areas of varying degrees of softness are relatively smallas compared to the entire wheel perimeter. Thus, on any narrow bandaround the wheel surface there may be as many as fifty or a hundred ormore successive areas which are of different degrees of softness,interspersed in such manner that as the wheel makes each revolutionthese different incremental areas come successively into play. Also,there may be few or many degrees of softness included in thesesuccessive incremental areas. or five distinct degrees of softness inthe areas, but the exact number used will be a matter of choice on thepart of the operator as will presently appear. Usually these areas of;different degrees of softness will be interspersed. according to aregular pattern, such pattern including the various degrees of softness,and the entire wheel perimeter area being covered by such patterns whichare repeated frequently over such wheel surface. Each incremental areamay be of selected form, such as circular, rectangular, hexagonal,square, oval, or of any selected form. Sometimesthe entire perimetersurface of the wheel, over which the abrasive belt travels, may beoccupied by such incre: mental areas, without interstices between thesuccessive incremental areas; sometimes said incremental areas will notcome into direct perimeter contact with each other, but will be spacedapart to a greater or less extent as de cided by the designer of theequipment. When such in-. terstic'es are included between the adjoiningincremental areas it is evident that, when each such incremental area issubjected to pressure, due to the forcing of the work object againstthebelt travelling on such incremental area the material of such area maybe forced laterally into such interstices by the compressive actionproduced by such work and belt pressure. When such interstices are notprovided between the successive incremental areas it is evident that thedeformations of such incremental areas will be accompanied by lateralcompressive forces exerted against the adjoining incremental areaelements of different degrees of softness.

I have herein disclosed several embodiments of device including thefeatures of my present invention, and disclosing various forms includingboth the interstice arrangement and other arrangements in which suchinterstices are not included.

It is evident that when the contact wheel is at rest no centrifugalaction is produced on the incremental areas of different degrees ofsoftness. However, when the wheel is at speed very considerablecentrifugal forces are i developed in. these areas. -These' areas areformed of:

material such, as rubber of varying degrees of softness, or of othersuitable elastic material, Thesevarrous soft nessareas are,'however,ofmore or less thesame specific gravity so the centrifugal forcesdeveloped in thevarious incremental areas are substantially equal inamount at any given wheel running speed. Any radial enlarge ment' of anarea due to its elasticity and the centrifugal force being developedduring running will somewhat aggerate the centrifugal force sodeveloped, but for the present discussion we shall momentarily disregardsuch radial enlargement effect on the centrifugal force developed at agiven running speed. Under this assump-;

tion it is evident that each incremental area will expand;

radially under wheel running, and also that the amount of such radialexpansion of each area will-be more orless'dependent-on the degreeof-softness of such 'areas As a simple example, use may be made of four5 material. That this is true will be seen from an application of thetheory of elasticity and use of Youngs modulus of elasticity to theproblem. It is to be assumed that all of the incremental areas arecomposed of materials having substantially the same specific gravity sothat the centrifugal forces developed in said areas are of substantiallythe same value (the sizes of the areas being substantially equal), andif it be assumed that Youngs modulus is smaller in the case of therelatively softer materials than it is in the case of the relativelyless soft materials, then e=Fl/MA for each incremental area, where; eequals the elongation, F equals the total force exerted to produce theelongation (being the centrifugal force developed in each of theincremental areas), l equals the length of the body of the incrementalarea in the direction of its stretch (being its length radially), Mequals Youngs modulus for the material of such incremental area, and Aequals the cross-sectional area of such incremental area. Under theassumed conditions, if all of the bodies of the incremental areas are ofthe same radial length, initially, and are of substantially the samecross-sectional area, then each such body will suffer stretch radiallyby an amount substantially inversely proportional to its Youngs modulus,and therefore substantially proportional to its softness degree. Thismeans that the areas of greater softness will extend radially to agreater amount than those areas of less softness, it being assumed thatthey were all of substantially the same radial dimension to begin with.If they were not all of the same radial dimension to begin with (whenthe wheel is at rest) each of them will suffer a radial elongationmodified from that previously stated from the elongations of other areabodies in the same proportion which such body bears in original lengthto the original lengths of the other bodies. In each case, however, theelongation of each body under centrifugal force during running (and whennot affected by other modifying influences, such as the pull of thebelt, and the applied pressure of the work object), will be greater forthe softer materials areas, per inch of original radial dimension, thanfor the less soft materials.

In practice, the incremental area bodies are applied :to or built intothe wheel periphery surface by an as- :sembling operation. When this hasbeen done the exposed or perimeter surfaces of these bodies should beground to proper dimensions and finishes. Such grinding may be effectedwhen the wheel is at rest or may be effected while the wheel is runningat a predetermined or specified speed, generally much less than itsnormal running speed when grinding and polishing operations are beingeffected. Or such grinding may be effected while the wheel is rotatingslowly so that substantially no centrifugal effect is being produced onthe various incremental area bodies. In any case, however, such grindingoperation will bring the exposed or peripheral surface areas of thevarious bodies to a common cylindrical surface at the speed and underthe conditions under which the grinding is performed. If the grinding isperformed with the wheel at rest or rotating so slowly as to producesubstantially no centrifugal effect, then, when the wheel is at rest allof the working surfaces of the bodies will lie within that cylindricalsurface to which said bodies were ground. If the grinding is performedwith the wheel rotating under a speed sufficient to produce a materialamount of centrifugal force in the bodies so that they are under strainat the time of such grinding, then when the wheel is at rest the softerbodies will contract radially more than the less soft bodies, and

will thus lie beneath that cylindrical surface to which,

less soft bodies have withdrawn. However, in any case, either thegrinding while the wheel is at rest, or the grinding whilethe wheel isrotating fast enough to pro duce some centrifugal force, when the wheelis brought up to normal working speed the softer body areas will expandunder centrifugal force sufficiently to carry their working surfaceareas out beyond the working surface areas of the less soft bodies, sothat the softer material bodies will project beyond the bodies formed ofthe less soft materials. Accordingly, the abrasive belt will travelprincipally on the incremental areas of the softer materials, when thework body is not pressed against the abrasive belt. When such work bodyis pressed against the abrasive belt said softer material body areaswill be compressed radially inwardly, the belt of course also beingcorrespondingly deformed, the extent of such inward deformationdepending on the amount of force exerted against the belt'by the workbody at such time.

If the pressure of the work body against the abrasive belt be light sothat the radial inward movement is not suflicient to bring the belt intogood engagement with the less soft bodies, then the abrasive effect willbe due solely to pressure resistive efiects produced by the softermaterial bodies. If, on the other hand, the pressure of the work bodyagainst the belt be increased sufliciently said softer material bodieswill be compressed sufiiciently to allow the belt to also run on otherbodies of less soft materials, which have not been centrifugallyprojected as far as the softer material bodies. Under this newassumption of an increased pressure of the work body against the belt itis evident that the resistive effects of at least two sets of bodieshave come into playthe softer material bodies originally in effectiveoperation, and now the additional less soft material bodies thus broughtinto play. Further, it is evident that the radially inward deformationsof the original soft bodies are always greater than the radially inwarddeformations of theless soft bodies which have only afterwards come intoplay. Further, it is evident that, once the pressure of the work againstthe abrasive belt has been raised sufficiently to bring the less softbodies into operation, not only has the effective pressure exerted bythe softer bodies been increased, but additionally thereto a furtherpressure has been developed by the less soft bodies as they come intoplay; and, since these less soft bodies have a greater value for Youngsmodulus than the softer bodies it is evident that a given amount offurther deformation of the belt by the pressure of the work body againstsuch belt must be accompanied by a greater proportionate increase inabrasive pressure exerted on the belt at the locations of the less softbodies than at the locations of the original softest bodies.

By providing a number of groups of bodies of different degrees ofsoftness, it is possible to produce operations involving a correspondingnumber of effects from Areas of bodies rated at 40 Durometer, expandedto 17 inches diameter.

Areas of bodies rated at 50 Durometer, expanded tol6 inches diameter.

Areas of bodies rated at 60 Durometer, expanded to 15 /2 inchesdiameter. Areas of bodies rated at inches diameter. I Areas of bodiesrated at Durometer, expanded to 14 /2 Durometer, expanded to 15 inchesdiameter. r v

Areas of bodies rated at 90 Durometer, expanded to 14% inches diameter.

The foregoing shows clearly therelationship between the degree ofsoftness and the effect of the centrifugal action on the various groupsof bodies. It'will be understood that the expanded diameters statedabove are the diameters towhich the bodies may beexpected to expand whenthe belt is not in contact with the bodies on the wheel so that they arefree to expand naturally under centrifugal action. Since the abrasivebelt is in contact with substantial-ly one-half of the periphery of thewheel or with the elemental areas of those bodim lying oversubstantially one half of the wheel circumference it follows that theeffect of the contact of the belt with such elemental areas of suchbodies must be explored as follows:

The amount of expansion'of the softer bodies will be reduced by theengagement of the belt with them. The amount of such redu tion ofcentrifugal force expansion will depend largely on the belt tension. Ihave already referred to the provision of spring means to enablemaintaining the desired tension in the belt and to allow for slight backand forth movements of the tensioning wheel so as to maintain thedesired tension of the belt on the contact wheel as now being discussed.By properly adjusting the tension in the belt it is possible topredetermine the differential between the centrifugally expanded softestmaterial bodies and those bodies of less softness to thus vary theoverall effects produced during a given running of the wheel, and theeffects produced on the work object corresponding to such operation.

It is also to be seen that the pressing of the work object against theabrasive belt of itself modifies the extent of expansion of the variousbodies and correspondingly affects the compressions of those bodies atthe location of such work object. This has already been referred toherein. As the wheel rotates and the belt travels to and in contact withthe work object (and thereafter away from such work object) each of thecompressed bodies exer'ts a pressure urging the belt into contact withthe work object under a corresponding pressure. Since the successivebodies are of different degrees of softness and are under differentamounts of pressure against the belt it follows that the pressure beingexerted to urge the abrasive surface into contact with the surface ofthe work object suffers rapid variations and is not a uniform pressure.These variations of pressure may be large in amount, and they may besudden or of a graduated nature of change in amount. In any case thesevariations in pressure are of great rapidity and continue during theentire operation. For example, in the case of a wheel presenting aworking surface of substantially 15 inches diameter when running, andwhich wheel is provided with fifty bodies around its circumference atany given plane normal to the axis of rotation, at a rotative speed of1750 R. P. M. there will be 87,500 bodies passing the work object perminute. Each of these bodies will cause an increase of pressure duringapproach and a decrease of pressure during recession of the body awayfrom the work object. Correspondingvariations in the abrasive pressurebeing exerted on thework body by the abrasive belt will occur. Thesevariations in the working pressure of the abrasive surface against thework object will greatly improve the abrading action, and will alsogreatly increase the cutting action so that much more rapid operationswill be produced under a given set of conditions of work object and rateof belt travel.

A prime object of the present invention is toprovide a method or mode ofoperation for conducting the grinding and/or polishing which methodincludes the features hereinbefore disclosed. I

It is a further object of the invention to provide the means to performthe grinding and/or polishingoperations according to such method.Accordingly I have-il-- that the effects of the various degreesofsoftness shall be intermingled or interlaced during the running of thewheel. Specifically, I have providedarrangementswherein suchintermingling or interlacing may be produced according to anypreselected pattern, and whereby such pattern may be changed from timeto time very conveniently by the operator to meet varying operations,and according .to varying needs imposed by thegrinding and/ or polishingto be effected, and the specifications.. df finish desired to besecured.

Other objects and uses of the invention will appear from a detaileddescription of the same, which consists in the features ofconstructionand combinations of parts hereinafter described and claimed.

In the drawings:

Figure 1 shows a plan view of a typical contact wheel including oneembodiment of the present invention wherein the elastic bodies compriseblocks of uniform design, and wherein said blocks are retained in placeand locked to the body of the wheel by tongue and groove arrangements;said blocks being formed of elasticv Figure 3 shows a crosssection takenon the line 1 of Figures, 1, 4 and 5, lookin g in the directions .ofthe, arrows; and in this figure I have shown one'form of reinforcingelement in the base portions of the various elastic blocks, whichelement serves to prevent radial withdrawal of such block from the wheelunder centrifugal action;

Figure 4 shows a development of a portion of the peripheral portion ofthe wheel of Figures 1, 2 and 3 and it shows one pattern ofinterspersing of the bodies of the several degrees of softness so thatdesired effects are produced;

Figure 5 shows a longitudinal section through the wheel of Figures 1, 2and 3, being taken on the line 5 5 of Figure 3, looking in the directionof the arrows; and this figure is also a section taken on the line 5-5of Figure 4, looking in the direction of the arrows;

Figures 6 and 7 are face and edge views, respectively, of one of thebodies of elastic material used in the type of construction shown inFigures 1, 2, 3 and 5.; and'the se Figures 6 and 7 show areinforcing'element comprising a U- sh-aped unit of stiff wire, embeddedand moulded in the'base of each of the elastic bodies, and of size suchthat said body may not be displaced'nor withdrawn from its lockingengagement with the wheel under cens trifugal or other action; i

Figure 8 shows a perspective view of a modfiedform of elastic body orblock for use in the construction of Figures '1, 2, 3 and 5, in whichmodification the re inforcing element for each elastic block comprises aplate of" metal, preferably foramin'ated, embedded and moulded in thebase of the elastic block, and of size to prevent withdrawalof the blockfrom the locking engagement with the wheel body;

Figures 9 and 10 show, on enlarged'scale'as com-f pared to Figuzre 8, aface view and an edge view of the foraminated reinforcing plate used .inthe arrangement ofFigure 8; i

Figures 11 and 12 show a face view and an edge view,

respectively, of another modified form of elastic block" streets for usein connection with the construction shown in Figures 1, 2, 3 and 5; andin this case of Figures 11 and 12 the reinforcing comprises a U-shapedplate of sheet metal, foraminated, and embedded and moulded into thematerial of the elastic block, and of form to prevent radial withdrawalof the elastic block from the wheel body; and the reinforcing shown inFigures 11 and 12 is also designed to produce a desired control of theradial expansion of the elastic block under centrifugal force to bedeveloped during the running of the wheel in service, to thus ensure adesired and proper contour of the outer or working surface of theelastic block under working conditions;

Figure 13 shows a detail view of another form of the reinforcing elementfor embedding in the base portion of the elastic blocks, being a stiffwire element formed into almost a closed rectangle, instead of being ofU-shape as in the case of the reinforcing elements shown in Figures 6and 7;

Figure 14 shows a cross-section through a modified form of contact wheelconstruction embodying the features of my present invention; and in thepresent case the wheel body is provided with numerous longitudinally oraxially extending rods having their ends properly supported in rigidrelationship to each other, and the elastic bodies or blocks are strungon these rods in overlapping relationship so as to cause said bodies tobreak joints with each other; and in the present construction I haveprovided radial supporting plates strung on the wheel shaft and alsostrung on the aforesaid rods at locations intermediate between thecircularly aligned bodies or blocks and serving to give support to therods against radial displacement under centrifugal forces developedduring running, and also giving support to the elastic blocks to retainthem against rocking movement on the rods whereon such blocks arestrung; and this figure shows a broken cross-section wherein thecircular semiportion above the horizontal medial line is taken on theline 14a14a of Figure 15, looking in the direction of the arrows, andwherein the circular semi-portion below the horizontal medial line istaken on the line 14b14b of Figure 15, looking in the direction of thearrows;

Figure 15 shows a development of a portion of the peripheral surface ofthe wheel shown in Figure 14, the locations of the radially extendingplates being shown by dotted lines;

Figure 16 shows a longitudinal section taken on the line 16-16 of Figure14, looking in the direction of the arrows;

Figures 17 and 18 show face and edge views, respectively, of one form ofbody or block of elastic material for use with the wheel constructionshown in Figures 14 and 16; and in this block construction I haveprovided a reinforcement embedded and moulded in the base of the block,and comprising a U-shaped plate of sheet metal which is foraminated, andwith the arms of such U-shaped elementperforated to receive the rod onwhich the block is strung; the reinforcement element being designed andformed to control theradial expansion of the block under centrifugalforce effect to ensure production of the desired contour of the outerworking surface of the block when the wheel is running;

Figures 19 and 20 show face and edge views, respectively of another formof reinforcing element for the blocks to be used in the wheelconstruction shown in Figures 14 and 16; and in this case thereinforcing element comprises a curved plate of foraminated sheet metalembedded and moulded into the base portion of the elastic block;

Figure 21 shows a perspective view of another form of reinforcingelement for use in the elastic blocks of the wheel construction ofFigures 14 and 16; and in this case such reinforcing element comprises alength of stiff wire formed to provided spiral spring sections to surround and receive the rod on which the elastic block is strung, and alsoto provide laterally projecting wings at the two sides of such spiralspring sections, so as to ensure better adhering connection to thelateral portions of the elastic block and better control of the radialexpansion effects produced on the block under centrifugal force effects;V

Figure 22 shows a face view of another form of stiff wire reinforcingelement for embedding and moulding into the base of the elastic block,and it comprises a spiral spring section to receive the rod on which theelastic block is strung, together with a single laterally extending wingelement;

Figure 23 shows a face view of an elastic block having embedded andmoulded therein two of the reinforcing elements of the form shown inFigure 22, such elements being set together with their wings extendinglaterally in opposite directions;

Figure 25 shows a cross-section through another modified form of wheelembodying the features of the present invention; and in the constructionshown in this figure I have provided the wheel body with a cylindricalsheet which is provided with numerous openings through which. theelastic blocks may be radially extended from the inside of suchcylindrical sheet, the bases of such blocksbeing so formed that saidblocks are retained against out- I throw under centrifugal forcedeveloped during the running of the wheel; and the bases of theseelastic blocks :are provided with suitable reinforcing elements (notshown in Figure 25, but shown elsewhere), which are so formed as toprevent the bases of the blocks from pulling through the opening-s ofthe cylindrical wheel sheet; and Figure 25 is a section taken on thelines 25-25 of Figures 26 and 29, looking in the directions of thearrows;

Figure 26 is a development of a portion of the peripheral surface of thewheel shown in Figures 25 and 29;

Figures 27 and 28 are a face view and a bottom or inside view,respectively, of the elastic block incorporated into the wheelconstruction shown in Figures 25 and 29; and this elastic block isprovided with :a ring of stiif wire embedded and moulded into the baseportion of such block, and of size to retain the elastic block againstpulling through the opening of the cylindrical wheel sheet;

Figure 29 shows a longitudinal or axial section taken on the lines 29-29of Figures 25 and 26, looking in the directions of the arrows;

Figure 30 shows a fragmentary development of a portion of the peripheralsurface of the wheel of Figures 25 and 29, but with such wheel providedwith square bodies or blocks of elastic material set into diamond posi'tion in thewheel surface, when considering the direction of surfacemovement;

Figure 31 shows another modified form of body or elastic block for usewith the wheel construction of Figures 25 and 29, the, blocks in thiscase being hexagonal in cross section, and set with their faces normalto the direction of wheel surface travel;

Figure 32 shows another view similar to that of Figure 31, but with thehexagonal cross-section blocks set with their edges facing in thedirection of wheel surface travel;

Figure 33 shows a longitudinal section through one of the blocks of thetype shown in Figure 30, being a detail section taken on the line 33-33of Figure 30, looking in the direction of the arrows;

Figure 34 shows a top plan view of the block shown in Figure 33;

Figure 35 shows a top plan view of another modified form of block whichmay be used in connection with the type of wheel construction shown'inFigures 25 and 29, the block in this case being oval or elliptical incrosssection, and set with its major axis parallel to the direction ofwheel surface movement;

Figure 24 shows an edge view corresponding to Figure Figure 36 shows aview similar to that of Figure 35, but with the oval block set into thewheel periphery with its major axis normal to the direction of wheelsurface movement;

Figure 37 shows schematically a typical installation of grinding and/orpolishing equipment incorporating the features of the present invention;and in this case I have shown a contact wheel of the general form shownin Figures 25 and 29, but only for convenience of illustration; and inthis figure I have shown the elastic blocks as being fully extendedradially due to centrifugal action, but have not shown modifications ofthe block extensions caused by belt pressure over the are of beltcontact with the wheel surface; and in this f gure I have shown butthree groups of the elastic material blocks,

being of three degrees of softness, the blocks of these three groupsbeing interspersed around the wheel surface; and in this figure I haveshown the effect caused by the pressing of a work body surface againstthe abrasive belt ata, given location of the contact wheel;

Figure 38 shows diagrammatically the centrifugally produced radialextensions of elastic bodies of four degrees of "softness, and themanner in which the chords of-contact of the work body against such anarrangement depend both on the softnesses of the respective materials ofwhich the elastic bodies are made, as well as the deformation pressureof the work body against the wheel surface; and

Figure 39 shows diagrammatically a development of the deformationsurfaces of the various elastic bodies shown in Figure 38.

1 Referring to Figures 1 to 13, inclusive, I have therein show-uhcontact .wheel construction embodying the feathree of my presentinvention in simple form, but consistently with widely acceptedconventional practice in the general arrangements of such wheels as usedin connection with abrasive belts travelling overthem. In the case ofthese figures I have shown the end portion of a spindle t) which issuitably journalled by journals not shown in the figures, so that saidspindle extends horizontally towards the observer in Figures 1, 2, 3 and5. This spindle is shown as provided with a rather large body 51 ofgenerally cylindrical form, and beyond such enlarged body 51 the spindleterminates in a threaded stem 52 on which the locking nut 53 isthreaded.

The body portion 51 is provided with a series of axially extendinggrooves 54 (12 being shown in Figure 3). These grooves are laterallyundercut as shown at 55 and 56 so that the elastic blocks presently tobe described may be set axially or endwise into the several grooves innumber sufficient to fill the axial dimensions of the grooves. Theseblocks are provided with laterally extending tongues to enter into andlock with the undercuts 55-and :56 as is clearly evident fromexamination of Figure 3. Thus the blocks are locked into the grooves toprevent radial outward movement of the bases of the bloeks'during wheelrunning. 7 V

The number of grooves which will be provided around the wheelsperimeter-lies within the choice of the designer, and likewise theaxia-llengths of the body portion 51v and thus of the grooves is a matter ofchoice of the designer; but it should be noted that such axial lengthshould'be sutlicient to accommodate the maximum size of work body to betreated by the machine inquestion. In Figures 1, 3, 4 and 5 I have shownprovision for only sir; full sized blocks and additionally-a half-sizeblock in each groove, but evidently the spindle body 51 may be made ofsufiicient axial length to accommodate many more blocks than indicated;and conversely, the number of blocks which may tie-accommodated within agroove of determined axial dimension will depend on the widths of theblocks (their dimension axially). In the figures'just referred to, andFigure 2, I hav shown 12 grooves around the wheel circumference. The

number of these groovesi will likewise be a matter of choice on the partof the designer, and will also be aflected by the desired diameter ofthe wheel. In deter-. mining the number of such grooves account may alsobe taken of the number of groups of blocks to be used; assuming thateach group includes blocks of a specified softness. When the number ofgrooves is a full multiple of the number of groups of blocks it ispossible to set the blocks into the wheel body under a pattern of blockdistri-' bution which is uniform over the entire wheel perimeter. Afront end plate 57 is set onto the projecting stem 52, and a block 58 isconveniently set between this end plate 57 and the nut 53 as well shownin several of the figures. By this arrangement it is possible to secureall of the blocks in place on the wheel, and by proper proportions ofthe parts, to ensure slight endwise pressure against the sets of blocksoccupying the various grooves, Since the blocks are formed of rubber orother suitable elastic material, and since considerable centrifugalforces are developed during running of the Wheel at speed, it is evidentthat ample provision must be made to ensure against out-throw of theblocks even against the tongue, and groove provision shown in thesefigures. Accordingly, I have made provision for reinforcing the bases ofthe blocks, and for amply preventing any such out-throw. Thus, each ofthe blocks shown in Figure 3 is provided with a U-sh'aped stiff wireelement 59 embedded and moulded into its base portion, and of size andplacement such that portions of such reinforcements extend Well into theoverhangs of the grooves 54 when the blocks are set into place. Suchfact is well apparent from examinaion of Figure 3. With this arrangementit is evident that no block can be thrown centrifugally out from thegroove without tearing the base portion of the bloc apart.

Various modified forms of reinforcing elements for the blocks to be usedin the embodiment of the invention now being described, are also shownin Figures 8 to 13, inclusive. Thus, in Figures 8, 9 and 10 there isshown a form of reinforcement comprising a fiat plate 60 of length suchthat the ends of said plate reach into the undercuts of the grooves 54.Such plate is forarninated I to include the numerous openings 61 throughwhich the elastic material extends and within which such material ismoulded to bond the base of the block into a well integrated body. Inthe arrangement of Figures 11 and .12 the reinforcement comprises asheet metal element of U-shape, set into the base portion of the block,and with its flanges 62 and 63 lying parallel to the faces of the block,and with its connecting or central portion 64 set intothe lower portionof the blocks base. This portion 64 is also shown as being of lengthsufficient to reach" into the undercut portions 55 and 56 of the groove,for the reason already explained in connection with the descriptions ofother blocks. Preferably, also, this reinforcing element is foraminated,at least inits side flange portions 62 and 63, as shownin Figure l-l. InFigure 13' I have shown another form of reinforcing element simi' lar tothat shown in. Figures 6 and'7; but in the case" of Figure 13thereinforcing element is formed into 3.1- most a closedrectangularelement, and, for that matter; the end portions 65. and 66might be brought together'to close the gap between them; i iVarious'other forms of reinforcing element will suggest themselves. to.the designer or student of this specification, and I do not intend tolimit myself tothe forms shown; in the drawings, except as I may do soin the claims to follow.

At this pointI wish to. call' attention'to the fact that i under thecentrifugal forces developed during wheel run-.9

ning the radial expansions of the,b1oeks will. bev determined by theresistive forces. developed within the blocks.

h lves n which r sistsuch radial expansions} 111-.

cluded in such resistive: forces is the effect of, thev rein, forcingelement embedded; into andibond d tothe base: 7 r portion of each of theblocks. Evidently such rein-forcing element has .afar higher tensilestrength and modulus of mamas 13 elasticity than the elastic material ofwhich the body of the block is formed. Accordingly, it is seen thatthose portions of the elastic body which are in radial alignment withportions of the reinforcing element, which portions of such reinforcingelement are capable of effectively receiving and retaining expansiveforces and resisting them, will have their expansions under centrifugalaction greatly modified by the reinforcing element. By proper design andplacement of the reinforcing element within the clastic block it ispossible to ensure a desired contour of the outer perimeter surface ofthe elastic block when under running speed. It is not deemed necessaryto here explore the exact relationships between reinforcing element anddesign of the elastic block to secure the desired result, but if need besuch design might be based on'empirical tests and reformations of designfrom a calculated design.

In the embodiment shown in Figures 1 to 13, inclusive, I have shown, byway of illustration only, four groups of the elastic blocks, of fourdifferent degrees of elasticity. These are conveniently designated as A,B, C and D blocks. Assuming that there are the same number of blocks ineach of these groups, it is generally desirable to distribute the blocksof the several groups over the perimeter of the wheel according to aselected pattern. Preferably, also, such pattern is so selected that anyelemental area of the work object which is being held in contact withthe abrasive belt will be subjected to the influence of the blocks ofthe several degrees of softness in regular succession, and according toa pattern of softnesses. To accomplish this result the user of thecontact wheel will set the elastic blocks into the various grooves insuch order or progression around the wheel, and in such successionaxially of the wheel, as to produce on the perimeter of the wheel thatpattern which he desires to use. It will also usually be desirable to beable to break joints in the pattern thus finally produced so that noelemental area of the work object may continue in contact with acircumferential joint around the wheel for more than the length of oneblock continuously. The number of possible patterns which may beproduced on the surface of a wheel of conventional size, for example,14-15 inches diameter, is very large, even when using only three or fourdegrees of softness. 7

Since it is desirable to set the blocks into place in such pattern as tobreak joints, as already referred 'to, it is needful to make use of someblocks which are of less than the normal full width assigned to theblocks. Conveniently these partial width blocks are made of half width,in which case the joints between blocks may be brought to align with thecentral portions of preceding and following blocks. Likewise, a moreregular and orderly pattern may be produced when using such half sizeblocks than when using blocks of either greater or lesser widths thanhalf width for production of the joint breaks.

In Figure 4 I have, by way of illustration,'shown one pattern which maybe produced on the wheel now being described, when use is made of fourgroups of blocks, of four degrees of softness. The direction of wheelsurface travel is shown by the arrow 67 in this figure. It will be seenthat any elemental area of the work object held in contact with the beltat a given point will be subjected to the blocks of the several groupsin the order progressing from A backwardly through D, C and B back to A.That order might have been reversed by setting the blocks into the wheelgrooves in reverse order fashion. It will also be seen that actuallysuch elemental area of the work object will be influenced by th blo s inthe ordar A, A, D, D, C, C, and B, B, and back to another block of the Agroups.

Examination of Figure 4 will also show the use of the half width blocksto enable the breaking of joints as referred to.

The radial dimensions of the blocks when originally installed into thewheel should be somewhat greater than will be required for the wheelspecifications to be com- 14 plied with. Such excess need not be large.Then, when the assembly of all of the blocks into place has beencompleted, and the wheel end plate has been locked into position, theouter perimeter of the wheel may be somewhat uneven, and in any caseslightly oversize, it being understood that the wheel is then at rest.The outer wheel perimeter may then be subjected to a grinding operationto bring all of the outer faces of the blocks to a common cylindricalsurface of specified size, within the allowed tolerance. Such grindingmay be effected with the wheel rotating slowly so that substantially nocentrifugal effect is produced on the various blocks, or under a speedsuflicient to bring about some centrifugal enlargement during thegrinding operation. This has already been referred to in the preamble,and need not be further repeated here. Reference will be made to thismatter hereinafter.

The operation of the wheel shown in Figures 1 to 13 under belt runningconditions will be considered hereinafter.

In the construction shown in Figures 14 to 24, inclusive, the spindle 68is provided with an extension 69 of reduced size and has its front endthreaded to receive the locking nut 70. The block 71 is set against ashoulder 72 at the junction of the extension 69 with the spindle, andthe wheel end plate 73 sets against the said shoulder. A spacer sleeve74 is set onto the extension 69 and reaches forwardly to the front endof the wheel. There the front plate 75 is set onto the extension 69 oronto the sleeve as shown; and a block 76 is set onto the extension 69and is clamped towards the end of the sleeve 74 by the nut 70. The frontend plate of the wheel, 75, is set just inside of the block 74.

A series of rods 76 extend between the front and back end plates 73 and75, all of said rods being located at the same radial distance from theaxis of rotation of the wheel. Conveniently these'rods are extendedthrough the front end plate 75 and are threaded into the back end plate73, as shown, so that by pulling these rods up tightly a clamping actionmay be developed between the end plates 73 and 75.

A series of plates 77 are built into the body of the wheel. These platesare of the general form shown in Figure 14, from examination of whichfigure it will be seen that each such plate has its periphery formed topresent flattened outwardly facing edges or supports 78 which arepreferably formed as chords normal to the radii which touch said chordscentrally; and between these chords each plate is provided withoutwardly extending cars 79. In the embodiment now being described thereare preferably provided an even number of the rods 76. Thus, each of theplates 77 is provided with a number of the ears 79 equal to one-half thenumber of rods 76, r

construction the plates 77 are angularly staggered in alter- 1 nation,so that the ears of alternate plates come into registry, with theirsupports 78 also in registry; and so that the ears of the intermediateplates also come into registry, with their supports 78 also in registry;and also shows that each of the rods is thus registered with andextended through the ears of alternate plates, and that successive rodspass through the ears of alternate plates.

In studying Figure 14 it must be remembered-that the upper and lowerhalves of this figure are sections taken at the locations of successiveplates, as is evident from examination of Figure 15.

The elastic blocks illustrated for use in connection with the embodimentof wheel now being described are shown in detail in Figures 17, 19 and23 in face elevation. From 15 these figures it is seen that such blocksare of generally quadri-lateral form, each including a circular arcuateouter perimeter 80, a chordal inner perimeter 81, and two radiallyextending sides 82 and 83, connecting the outer and inner perimeters.Each such block is provided with a transverse opening 84 of size tonicely pass or ride on the rod 76 on which such block is strung; andsuch opening 84 is so'placed with respect to the chordal perimeter 81 ofsuch block that when the block is strung on a rod at a location betweenthe ears of two plates which are separated by an intermediate plate, thechordal perimeter 81 of such block will contact with and be supported bythe support 78 of the plate which lies intermediate between the twowhose ears have been just referred to. When so strung onto the rod suchblock is thus retained against out-throw under centrifugal action bysuch rod, and also the block is supported against rocking movement onthe rod, in part at least, by engagement of its chordal perimeter 81with the support 78 of the intermediate plate. Conveniently thesesupports 77 are enlargedaxially by forming the sheet metal from whichthe plate is formed, at right anglesthat is, axially, as well showninFigure 16. In such case it is noted that such rightangularly formedportion or support must not extend beyond the limits of the chordalperimeter, 81 as such further extension would interfere with the chordalperimeters of the two angularly adjacent blocks.

It is intended that the blocks used in the embodiment now beingdescribed shall break joints. This fact is apparent from examination ofFigure 15. In that figure the plate locations where the ears 79 arefound are shown by the double dotted lines with the unbroken linebetween them, such unbroken line representing the surface of engagementof one of the blocks with the axially adjacent block. It is here to benoted that due the elastic nature of the blocks themselves it ispossible to assemble them on the rods whereon they are carried, with theears 79 between the faces of the successive blocks; and then, when theblocks are compressed slightly together their proximate faces willcompress at the locations of the ears sufiiciently to permit the outerperipheral surfaces of adjacent blocks to come into substantialcontinuity. For this reason there is shown in Figure 15 no actual spacebetween the adjacent blocks of each axial row. However, the blocks areso sized that when they are assembled on the successive rods their sides82 and 83 come successively into contact as well shown in Figures 14 and15. Thus when the blocks have been assembled and drawn into position asubstantially continuous outer perimeter surface is provided for thewheel. g

In Figures 14, 15 and 16 I have indicated the presence of three groupsof blocks of three degress of softness, the blocks of these three groupsbeingdesignated as A'," B, and C, respectively. Examination of Figure 15will show one typical pattern of distribution of the blocks of thesethree groups over the wheel surface to ensure a good distribution of theseveral softnesses over the entire-wheel surface. shown'by the arrow 85.

It is now noted that in'the arrangement of blocks schematically shown inFigures 1 to 13, there are. shown twelve blocks around the wheel at anygiven section, and there are shown six full blocks and one half sizeblock axially of the wheel, together with four groups of blocks offourcorresponding degrees of softness. These various figures are more orless schematic in form, and accordingly, in practice there might be, forexample, twice as many blocks axially of the wheel, as are shown. Insuch a case, or by using other ratios of numbers of groups p of blocksas compared'to the number of blocks around the wheel, and also ascompared to the number of blocks axially of the wheel, perfectdistribution patterns of the blocks of the several degrees of softness,over the wheelv surface, may be secured.

By comparison, examination of Figures 14, 15 and l6, i

The direction of surface travel is 1'6 showing the modified embodiment,will reveal that in this case there are shown only three groups ofblocks, of three corresponding degrees of softness, twelve blocks aroundthe wheel, and six full blocks and a half block axially of the wheel. Itwill be seen that this relation between the various factors enablesproduction of a perfectly uniform pattern over the entire Wheel surface,both circumferentially and axially.

Each of the elastic blocks used in the embodiment of Figures 14, 15 and16 is provided with a reinforcing element in its base portion. Severalsuch reinforcing ele: ment forms are shown in Figures 17 to 24,inclusive. Such reinforcements are not shown in the section of Figure 14but any one of the block forms shown in Figures 17 to 24, or other blockand reinforcement forms, may be used with the wheel construction nowbeing described. In the arrangement of Figures 17 and 18 thereinforcernent element comprises a U-shaped sheet metal;

unit having the side plates 86 and 87 connected bythe bottom connectingpiece 88, the side plates preferably being foraminated to. permit thematerial of the elastic block to extend through the reinforcing elementand be thus, well' moulded together. These foraminations are shown at89. These side plates 86 and 87 are alsoprovided with openingsregistering with the block opening 84, so that when the block isassembled onto the wheel faceof such reinforcing element facingoutwardly of'the 9 block. Under centrifugal force action thisreinforcing element may bend or yieldslightly in its extremities, if

so designed. I

In the arrangement of Figure 21 the reinforcing ele-j ment comprises, asingle length of. stiff wire formed toprovide the two laterally adjacentspirals 91 and- 92, to,-

gether with the wing 93 reaching outwardly at one sideof the element;and. another wing 94 reaching outwardly at the other side of theelement. Usually the wing 94 will comprise the end. portions of the.wire length, bent to approach each other, but, not actually integratedtogether, although such integration might be provided if desired. Thespirals, 91 and 9.2, are of size and are so placed as to register withthe through opening 84 of the block in which such. reinforcement.element is embedded and moulded, so that when the block is. in place onthe rod such reinforcement elementwill secure direct support byengagement with the rod. Such engagement will enable a, slight rockingmovement of the reinforcement element 2 to occur if need be, but usuallythis will not occur. How-- ever, it is, noted'that with this type'ofreinforcementthere will be some springiness in the reinforcement'itself,so that the wings. 93 and, 94 may deflect outwardly Lto a slight extentunder centrifugal force eifects,fthus enabling the block, when,under'strain, to have itsenlarged outer perimetersurfaceoftheexact-desired'contour.

' In Figurev 22 I have shown another modified form I V stifii wirereinforcing element for use with the type "of both of these elements.

Reference. to Figure 16 in particular the presence of the washers orcollars 97 at the central portions of the plates 77 of the embodimentnow being described.

These are riveted or spot welded or otherwise secured to the severalplates, and their central openings are of size to fit nicely on thesleeve 74. These washers or collars are also of thickness such that whenthe plates are assembled together their central portions will come intoengagement with the washers or collars of the adjacent plates, thusensuring correct spacing of the plates within the wheel body, takingaccount of the thicknesses of the several elastic blocks which have beenstrung on the rods. An extra washer or collar, 97 is provided at the endof the wheel last assembled, to ensure correct spacing at that end.

By forming these washers or collars of proper thicknesses, so that whenthe plates and Washers or collars have been completely assembled theirtotal axial length is slightly greater than the length of the sleeve 74,upon pulling the nut 70 up tight the various plates 77, the washers orcollars, and the wheel end plates 73 and 75 will be drawn solidlytogether, thus ensuring driving from the spindle 68 (and the block 71)to the plates 77, and thus also to the rods 76. Thereby drive will beensured directly from the rods to the several elastic blocks whichprovide the wheel surface.

In Figures 25 to 36, inclusive I have shown another modified embodimentof my present invention. In this case the spindle 98 is provided withthe extension 99 Whose front end is threaded to receive the locking nut100. The wheel body includes the back and front plates 101 and 102,respectively with the blocks 103 and 104 set onto the extension againstthe .outer faces of these plates. The cylindrical element 105 issupported by the peripheral portions of the plates 101 and 102, forwhich purpose said plates are conveniently shouldered as shown at 106 sothat the cylindrical element 105 will seat nicely onto the peripheralportions :of the plates 101 and 102 and against the shoulder when theplates are drawn towards each other. A number of through bolts 107extend between the plates 101 and 102 and serve to draw said platestowards each other.

The cylindrical element 105 is provided with numerous openings toreceive the elastic blocks, said openings being of form according to theblock form intended to be used. In the showing of Figures 25, 26 and 29said openings are circular in form, but as will presently appear, otherforms of openings and blocks are also illustrated herein. These circularopenings are designated 103 for the circular form blocks. They aredistributed over the cylindrical element 105 in regular fashion, andaccording to a pattern which is a consolidation of the patterns adoptedfor the blocks of the several groups of softnesses used in the wheel. Inthe arrangement shown in Figures 25, 26 and 29 this pattern of theopenings is one in which said openings are located at the apexes ofequilateral triangles, so that the openings lie in straight linesextending around the element 105 at the lines of intersection of planeswhich lie normal to the axis of wheel rotation; and the openings arethen set at positions on said straight lines such that the openingsbreak joints from line to line, as clearly evident in Figure 26.

A typical form of elastic block for use in such an opening and wheelarrangement as just described is shown in Figures 27 and 28. This blockis of cylindrical form, as shown at 109 and is of size to extend nicelythrough the openings To this end said cylindrical block portions are ofsubstantially uniform size or diameter. Each block is then provided withan enlarged base portion 110 which will engage the inner cylindricalsurface of the element 105 when the blocks are set through the openings108 so as to retain the block against radial out-throw under centrifugalforce, it being understood that the blocks are set through said openingsfrom the inside of the cylindrical element 105. These enlarged baseportions 110 are of size such that the bases of adjacent blocks do notinterfere with each other, although in some 18 cases said base portionsmay be of form such as to interlock for prevention of rotation of thevariousblocks on axes radial to the axis of wheel rotation.

In order to prevent possible out-throw of the blocks through theopenings 108 by dragging the base elements 110 through said openings, Ihave provided reinforcements in said base portions of the elasticblocks. In the form shown in Figures 27 and 28 such reinforcementcomprises a ring of stiff wire 111 embedded and moulded into theenlarged base portion 110, such ring being of size to underiie the innersurface of the cylindrical element 105 when the block is set through theopening.

The elastic blocks are set through the openings 108 prior to completeassembly of the element 105 to the plates 101 and 102, etc. When theblocks have been set through the openings an inner retaining cylindricalelement 112 may be inserted into the Wheel body, being of a size to slipnicely within the generally cylindrical surface which defines the innersurfaces of the blocks thus in place. Such inner retaining cylindricalelement 112 will then prevent shift of the blocks inwardly and willretain them in proper projected positions irrespective of centrifugalforces, and prior to wheel running. Such cylindrical element will alsoprevent forcing of the blocks inwardly under tension of the belt whichis afterwards run over the wheel. The engagement of the inner surfacesof the base portions of the blocks with the outer cylindrical surface ofthe element 112 will also prevent tilting :of the blocks although theblocks may be deflected by bending or like deformation, since they areformed of elastic material.

After the blocks have been assembled into the wheel, and the assemblingof the wheel has been completed, the outer surfaces of the blocks may befinished by a grinding operation, according to the principles alreadydisclosed herein.

The number of degrees of softness of the blocks used in this embodimentof the invention will be determined by the designer and according to theintended uses and specifications of use of the wheel, and need -not befurther explained beyond calling attention to the face that in thearrangement shown I have indicated five groups of blocks, designated asA, B, C, D and E blocks, respectively; and in Figures 25 and 26 I haveshown a simple form of pattern of distribution of these blocks over thewheel surface. 7 a

In Figures 30 to 36, inclusive, I have shown several modified forms ofthe elastic blocks intended for use in connection with the embodiment ofFigures 25, 26 and 29, and I have also therein shown other details ofpattern formation than that shown-in Figure 26. In Figure 30 I haveshown a fragmentary development of the wheel surface provided withsquare openings through which are extended square blocks, 113. The,bases of these blocks are also square and are of such size that thebases of the adjoining blocks come together edge to edge, thus lockingthe various blocks against rotation on their own axes, In Figures 33 and34 I have shown details of a square block intended for use with thearrangement of Figure 30, and I have shown the reinforcement element 114in the base of such block. This element 114 is of size such that itcannot be pulled through the square opening of the wheel element 105(corresponding to 105 of Figures 25 and 29). As shown in Figure 34 thisreinforcement element 114 may be square and placed with its sidesparallel to the sides of the square block, but evidently otherarrangements of reinforcement might also be used.

It is also noted that in the pattern of Figure 30 the openings throughwhich the blocks are set are rocked to an angle of 45 degrees withrespect to the direction of wheel surface travel, which direction oftravel is shown by the arrow 115 in Figure 30.

In Figure 31 I have shown a fragment of a development of a wheel surfacewhich is provided with blocks of hexagonal form extended throughcorresponding hexagonally formed openings. These blocks 116 of Figure 31are set into a pattern in which the flat. faces of the blocks lie normalto thedirection of wheel surface travel, shown by the arrow 117. InFigure 32 I have shown a fragment of a development similar to that shownin Figure 31; but in the case of Figure 32 the hexagonal blocks 118 areset into the wheel with their apexes facing in the direction of wheeltravel shown by the line or arrow 119.

In Figure 35 I have shown an elliptical or oval form of block, set withits major axis parallel to the line of wheel surface travel, 120, suchblock being shown at 121; and in Figure 36 I have also shown anelliptical or oval form of block 122, but set with its major axis normalto the direction of wheel surface travel as shown by the arrow 123.

Various other forms of blocks, and various other patterns ofdistribution of the blocks over the wheel surface will suggestthemselves to the user or student of this invention.

In Figures 37, 38 and 39 I have shown schematically various of theoperations which occur when using my improvements in grinding andpolishing, and when using equipment of the general type previouslydescribed in detail herein. The showings of these figures areexaggerated as to amounts of elastic extensions or radial enlargementsof the blocks of different degrees of softness,

this being done for better illustration of the nature of the operationsand the effects produced.

In Figure 38 I have shown by the circle 124 the working size of thesurface of the abrasive belt to which the work object is to bepresented, prior to contact of such object with such belt surface, itbeing assumed that the wheel is at speed. It is also assumed forsimplicity of explanation that the work surface to be presented to thebelt is flat. The flat worksurface is shown in several successivepositions as 125 125 125, etc. Upon pressing such surface slightlyagainst the belt surface so as to produce a slight deformation of theelastic wheel surface, to bring the work surface to the line 125 thelength of the chord over which scratching engagement will occur is shownbetween the points 126 and 127, and is relatively small. Furthermore,the pressure which must be exerted between the work surface and theabrasive belt is light. Thus a light cutting or scratching action isproduced, in the nature of a polishing operation.

It will now be assumed that the wheel surface is formed of elasticmaterial, but is homogeneous in character and composition. Under theseconditions, increase of pressure of the work surface against the wheelsurface will cause deformation to the line 125 Corresponding to this newcondition the length of the scratch has been increased to the distancebetween the points 128 and 129, and the pressure has also been increasedas already stated.

Upon further increase of the work pressure against the belt surface afurther increase of deformation will be produced, bringing the worksurface to the line 125. Then the lengths of the scratches will becomethat distance between the points 130 and 131. Finally, a furtherincrease of work pressure will shift the deformation to the line 125with increase of the lengths of the scratches to that distance betweenthe points 132 and 133.

It is thus apparent that when the elastic surface of the contact wheelis of uniform softness or yieldability over its entire surface, thelengths of the scratches will increase with increase of pressure of thework against the abrasive belt. Also, the entire operation which will beproduced for any given pressure of the work body against the beltsurface will be that due to the abrading engagement of the work bodysurface against the abrading belt under the condition that at all times,from one end of the area of deformation to the other end of such area,the abrading pressure exerted between the work object and the abradingsurface is that pressure which causes deformation of elastic material onthe wheel surface, of one and only one degree of softness over theentire extent of the deformation which is momentarily produced by theworking pressure then in force. For any value of the working pressure ofthe object against the abrad-ing belt surface there will be produced acorrespondingtotal deformation, accompanied by a corresponding totallength of scratch. Also, the pressure per unit area, of contact of thework object against the belt surface will rise from zero to a maximum,and then decrease back to zero. Also, the integrated sum of allincremental area pressures must total to the actual pressure of the workobject against the belt. Therefore, the material removing effect of sucha total operation is limited to that which will be produced by thesoftness of the elastic material on the wheel surface, which elasticmaterial has been assumed to be homogeneous in character.

In Figure 39 I have shown schematically the work areas producedcorresponding to the increasing pressures of the work object against thebelt, for the several pressures referred to in Figure 38, and whichproduce deformations to the lines 125*, 125 and 125 respectively, suchwork areas being designated as 134, 135, 136 and 137, respectively.These showings are of course diagrammatic only.

Now let it be assumed that the surface of the contact wheel is providedwith elemental areas of various degrees of elasticity, such areas beinggrouped into four groups A, B, C and D, according to the principlespreviously disclosed herein. Then let such wheel be brought to speedwith the abrasive belt in working contact with the wheel. Under theseconditions let it be also assumed that the centrifugal forces developedin these incremental areas cause expansions of the various areas ofdifferent degrees of softness. Such expansions will be according to thesoftnesses of the bodies, the softer bodies suffering greater expansionsthan the less soft bodies. Let the circles 138, 139, 140 and 141represent the increased diameter paths of travel of the outer workingsurfaces of the several groups of incremental area bodies. The circle138 then corresponds to the softest bodies (A, for example), and thecircle 141 corresponds to the least soft bodies (D, for example). If,now, the work object be pressed against the belt travelling on suchcontact wheel, to produce a deformation to the line 125 in Figure 38,the following conditions will obtain: The softest bodies A will beforced inwardly from the circle 138 to said line 125 the least softbodies D will be forced inwardly from the circle 141 to said line 125and the bodies of intermediate degrees of softness will be forcedinwardly from the circles 139 and 14% to said line 125. The scratchesproduced by the softest bodies A will extend between the points 132 and133 already referred to; but the scratches produced by the least softbodies and the bodies of intermediate degrees of softness will be ofdifferent lengths as follows: For the bodies 8, between the points 142and 143, for the bodies C, between the points 144 and 145, and for thebodies D (least soft bodies), between the points 146 and 147. Thus thelengths of the scratches produced by the various groups of bodies willvary somewhat inversely as the softnesses of the bodies comprising saidgroups.

It must, however, be further noted that the contact pressures which willbe developed at the various incremental areas of these various bodieswill differ from each other in a special manner, as follows: The softerbodies have the smaller moduli of elasticity, as has already beenpointed out. which must be applied to the various groups of bodies inorder to produce deformations in them will differ from each other, therate of pressure increase for a body D, for example, being much greaterthan for a body A. That is, for a given increment of deformationproduced in each of these bodies, the pressure applied to the body Thusthe rates of increase of pressures D will be increased as compared tothe pressure applied to the body A somewhat inversely as the respectivemoduli of elasticity of these bodies. The net results of this is that,although the actual amount of deformation produced in the body D asindicated in Figure 38 is much less than the actual amount ofdeformation produced in the body A, nevertheless the final pressure towhich the body D may be subjected may actually be as great as or evengreater than the final pressure to which the body A is simultaneouslysubjected, notwithstanding the differences in the amounts ofdeformations suffered by said bodies.

Thus, too, it is evident that with this arrangement, the actualpressures to which the several bodies are subjected do not vary directlywith the lengths of the scratches, but the relation of scratch length topressure is much different in the several groups of bodies. It will alsobe evident that it is possible to select bodies of such relativesoftnesses and other characteristics that desired lengths of scratchesmay be secured in combination with desired pressures against theincremental area bodies in order to produce a specified grinding and/orpolishing operation on the work object.

Reference may now be had to Figure 37 for a further showing of thenature of these operations. In that figure the contact wheel isdesignated 148, rotating on the axis 149, an idler wheel is shown at 150rotating on its axis 151, and the abrasive belt is shown as 152. Thisbelt travels over both wheels, and generally the contact wheel 149 isalso the driver. The shaft of the idler wheel 150 is convenientlycarried by journals which can shift back and forth with respect to theaxis of the contact wheel, so as to produce a desired tension in thebelt; and I have shown a spring 153 drawing the idler wheel away fromthe contact Wheel to produce the belt tension. The effect of this springmay be adjusted by'the operator to meet his requirements. Devices ofthis type are known and used in this art, and therefore I do not hereinillustrate or describe such a device with particularity. The directionsof wheel rotations are shown by the arrows 154 and 155.

The contact wheel 148 is provided with three groups of elastic bodies ofthree degrees of softnesses. These are designated as A, B, and C,respectively, the bodies A being the softest ones. In Figure 37 thesystem is shown as operating with the contact wheel at speed, so thevarious elastic bodies are shown as being fully expanded by centrifugalaction. Thus the bodies A are shown most expanded, and the bodies C areshown as least expanded, and the bodies B are shown under anintermediate amount of expansion. The belt is shown as running on theouter surfaces of the bodies A, since said bodies project the greatestamount; and in this figure I have, for purposes of illustration, shown asufiicient difference between the expansion of the bodies A and B sothat the beltis shown as passing tangentially between adjacent bodies Awithout contact with the intermediate bodies B and C. In actual practicethis condition would probably never occur, but the belt would actuallyride in contact with all of the bodies. This condition would be causedby the following further fact:

In Figure 37 I have not shown any deformation of the bodies lying to theleft side of the contact wheel 148, which deformation is actually causedby the belt pull. With the belt under tension those elastic bodies whichare in engagement with the belt will actually be deformed inwardly inamounts dictated by the various factors of the problems of elasticityaffecting such distribution, so that actually the belt will probably betravelling in contact with all of the bodies at the left side of thewheel. But due to the fact that these bodies are of various degrees ofsoftness, and the various factors which have heretofore been discussed,the abrading operations produced will still be according to theprinciples hereinbefore explained.

In Figure 37 I have also shown the effect of application of a work body156 to the belt under suflicient pressure to deform the belt and theelastic bodies to such an extent that all of the elastic bodies ofgroups A, B and C" are brought into operation. The work body illustratedis shown as presenting the flat surface 157 to the abrasive belt underthe foregoing conditions of operation.

-I claim: i

1. A contact wheel having a peripheral cylindrical running surface forarcuate travel of an abrasive surface, said contact wheel including abody section and a plurality of elastic bodies lying in a cylindricalzone at the exterior radial portion of the wheel, each body being ofsubstantially uniform degree of softness throughout its outer peripheralportion, said elastic bodies being of different degrees of softness andincluding a plurality of groups of bodies, the bodies of each groupbeing of substantially the same preselected degree of softness, and thebodies of the different groups being of different degrees of softnessand being located in said cylindrical zone, together with means toretain the elastic bodies within said zone.

2. Means as defined in claim 1, wherein said means to retain the elasticbodies to the body section of the wheel includes disconnectable meansconstituted to permit attachment and detachment of the elastic bodies toand from the body section of the wheel.

3. A wheel as defined in claim 2, wherein the means to connect theelastic bodies to the body section of the wheel comprises companiontongue and groove portions on the body section of the wheel and on theelastic bodies.

4. A wheel as defined in claim 3, wherein said companion tongue andgroove portions extend longitudinally of the wheel and substantiallyparallel to the wheel axis.

5. A wheel as defined in claim 4 wherein the groove portions of saidconnecting means comprise portions of the wheel body section and whereinthe tongue portions of said connecting means comprise portions of theelastic bodies.

6. A wheel as defined in claim 5, together with stiff reinforcingelements embedded in the tongue portions of the elastic bodies and ofsize to retain the tongues of the elastic bodies against removal fromthe companion grooves in a direction substantially radial of the wheel.

7. A wheel as defined in claim 2, wherein the means to disconnectablyconnect the elastic bodies to the wheel section of the wheel comprises aplurality of substantially parallel rods and means to connect said rodsto the wheel body section, and wherein the elastic bodies are providedwith through openings to receive said rods, and wherein the elasticbodies are strung on the rods.

8. A wheel as defined in claim 7, wherein said rods extendlongitudinally of the wheel and substantially parallel to the wheelaxis.

9. A wheel as defined in claim 8, together with reinforcing elementsembedded in the elastic bodies and including portions of saidreinforcing elements which lie between the axis of wheel rotation andthe rods on which said elastic bodies are strung.

10. A wheel as defined in claim 9, wherein said reinforcing elements areformed of spring material and include portions extending within theelastic bodies to positions laterally displaced from the plane whichincludes the wheel axis and the rod on which the elastic body is strung.

11. A contact wheel having a perpiheral cylindrical running surface forarcuate travel of an abrasive surface, said contact wheel including abody section and a plurality of elastic bodies lying in a cylindricalzone at the exterior radial portion of the wheel, each body being ofsubstantially uniform degree of softness throughout its outer peripheralportion, said elastic bodies being of different degrees of softness andincluding a plurality of groups of bodies, the bodies of each groupbeing of substantially the same preselected degree of softness, and thebodies of the different groups being located in said cylindrical zone,together with means to retain the elastic bodies within said zonecomprising a cylindrical element portion of,

the 'body section of the wheel, and providedwith radially extendingthrough openings, and wherein the elastic bodies extend through saidradially extending through openings and project radially beyond'theouter surface of said cylindrical element, and wherein each elastic bodyincludes a base'portion of larger sizethan'the through opening throughwhich such elastic body extends, said base portion'being locatedadjacent to the inner surfaceof the cylindrical element aforesaid,

12. A wheel as defined in claim 11, together with -a second cylindricalelement coaxial with the first mentioned cylindricalelement and of sizeto underlie the base portions' of the elastic bodies and retain saidelastic bodies against movement radially inwardly through the openingsof the first mentioned cylindrical body.

13. A Wheel as defined in claim 11, together with a reinforcing elementembedded in the base portion of each elastic body at a location withinthe cylindrical element, and comprising a stifi element having adimension in a surface parallel to the cylindrical element whichdimension is greater than the size of the opening in the cylindricalelement which opening accommodates such :elastic body.

14. A-contact wheel having a peripheral cylindrical running surface, apliable belt having an abrasive surface and travelling on said contactwheel surface, said contact wheel including a body section and aplurality of elastic bodies lying in a cylindrical zone at the exteriorradial portion of the wheel, each body being of substantially uniformdegree of softness throughout its outer peripheral portion, said elasticbodies being of different degrees of softness and including a pluralityof groups of bodies, the bodies of each group being of substantially thesame preselected degree of softness, and the bodies of the differentgroups being of different degrees of softness and being located in saidcylindrical zone and adapted to present outwardly facing incrementalareas of belt supporting surface, said elastic bodies being located atpositions within the cylindrical zone to present at said belt supportingsurface a pattern of said incremental areas of the different degrees ofsoftness which pattern is of pre-determined specification, together withmeans to retain said elastic bodies in said cylindrical zone.

15. A wheel as defined in claim 14, wherein said elastic body retainingmeans includes means to removably retain the elastic bodies in saidzone, and wherein the elastic bodies are interchangeable in saidcylindrical zone.

16. A Wheel as defined in claim '14, wherein the outwardly facing beltsupporting incremental areas all lie-in substantially the samecylindrical surface co-axial with the axis of wheel rotation when saidwheel rotates at a predetermined rotative speed. I

17. A method of treating 'anobject to the abrading effect of a pliablebelt having an abradingsur-face, which method consists in causing saidbelt to travel in contact with an elastic 'body member which includes aplurality of elastic bodies of different predetermined degrees ofsoftness and wherein the bodies of the different predetermined degreesof softness comprise a series of groups of said bodies and wherein thebodies of each group are of substantially the same-degree of softness,and wherein the bodies of the different groups are interspaced in thesurface of the elastic body member according to a preselected pattern ofthe bodies of the-several groups and wherein the bodies of the differentgroups are of different degrees of softness and which elastic bodymember travels at the same speed as the belt to thereby produceanelastic backing for said pliable belt which backing is ofdilferentdegrees of softness corresponding to said elastic bodies, and whichmethod consists in supporting the object to be treated in contact withsaid abrading surface of said belt under pressure, whereby theyieldability of the belt while in abrading contact with the object beingtreated is determined by the degree of softness of the backing body atthe location of belt engagement with the object being treated ateachinstant.

References Cited in the file of this patent UNITED STATES PATENTS

